namespace System.Collections.Immutable
{
    [DebuggerDisplay("Count = {Count}")]
    [DebuggerTypeProxy(typeof(ImmutableDictionaryDebuggerProxy<?, ?>))]
    [DefaultMember("Item")]
    public sealed class ImmutableDictionary<TKey, TValue> : ICollection<KeyValuePair<TKey, TValue>>, IDictionary<TKey, TValue>, IEnumerable<KeyValuePair<TKey, TValue>>, IReadOnlyCollection<KeyValuePair<TKey, TValue>>, IReadOnlyDictionary<TKey, TValue>, ICollection, IDictionary, IEnumerable, IImmutableDictionary<TKey, TValue>
        where TKey, notnull
    {
        [DebuggerDisplay("Count = {Count}")]
        [DebuggerTypeProxy(typeof(IDictionaryDebugView<?, ?>))]
        [DefaultMember("Item")]
        public sealed class Builder : ICollection<KeyValuePair<TKey, TValue>>, IDictionary<TKey, TValue>, IEnumerable, IEnumerable<KeyValuePair<TKey, TValue>>, IReadOnlyCollection<KeyValuePair<TKey, TValue>>, IReadOnlyDictionary<TKey, TValue>, ICollection, IDictionary
        {
            public IEnumerable<TKey>! Keys
            {
                [IteratorStateMachine(typeof(<get_Keys>d__18))]
                get;
            }

        }
    }
}